It was an ugly day for global stock markets. The Dow briefly wiped away all its gains for the year with all 30 stocks closing negative. European and Asian stocks also got crushed.

First, the scoreboard:

Dow:17,826.30, -279.47, (-1.54%)

S&P 500:2,081.18, -23.81, (-1.13%)

Nasdaq:4,931.81, -75.98, (-1.52%)

And now, the top stories on Friday:

Global stock markets got slammed. The Dow had its worst day of 2015. All 10 sectors of the S&P 500 closed in the red, and the Nasdaq, with the two other major indexes, closed negative for the week. What goes up must come down, says Brad McMillan, Chief Investment Officer at Commonwealth Financial Network: "Recently, there’s been much more up than down, which suggests today’s down is just an adjustment and nothing to worry about," he wrote in commentary. "As regular readers know, I start to pay attention when we get close to the 200-day moving average, and we’re nowhere near that point."

Earlier on Friday, stocks in China fell by more than 5%. Indexes in Italy and Spain fell by more than 2%, while the Dax in Germany lost 2.6%, the CAC in Paris lost 1.5%, and the FTSE in London fell 0.9%.

American Express shares posted the biggest losses on the Dow, falling nearly 5%. The credit cards and payments giant reported first quarter earnings Thursday that showed revenues missed forecasts but profits beat investors' expectations. On the earnings call, CEO Kenneth Chenault said the company plans to invest heavily in keeping its Costco customers, following the non-renewal of their exclusive co-branding deal in February. Barclays analysts lowered their estimates for profits, noting higher operating expenses.

In economic data, consumer prices fell in March. The headline Consumer Price Index fell 0.1% over the prior year, but on a "core" basis, which excludes the more volatile cost of food and gas, prices rose 1.8%. Prices were expected to be flat over last year and rise 1.7% on a core basis. Compared to last month, prices rose 0.2%, below expectations for a 0.3% increase, and on a "core" basis prices rose 0.2%, in-line with expectations.

Bloomberg terminals went down worldwide for nearly three hours on Friday morning. The terminals are an essential part of many traders’ setups to monitor market data, execute trades, and crucially, to instant message one other. Connection was restored before US stock markets opened, but the UK Debt Management Office had to postpone a treasury auction scheduled for 10 a.m. (London time) because of the outage. Traders panicked, turned to Reuters' data terminal, and laughed it off on Twitter.